A wire is bent in the shape of a right angled triangle and is placed in front of a concave mirror of focal length, $f$ , as shown in the figure. Which of the figures shown in the four options qualitatively represent(s) the shape of the image of the bent wire (These figures are not to scale.) [2018]

Question

Smart Achievers · Accepted Answer

(4)

$Distance of point A from the mirror is \frac{f}{2} .$

From mirror formula,

$\frac{1}{v} + \frac{1}{f / 2} = \frac{1}{- f}$ $\Rightarrow \frac{1}{v} = \frac{2}{f} - \frac{1}{f} = \frac{1}{f}$ $∴$ $v = f$

Image $A' B'$ of line AB should be $I$ principal axis. Image of $F$ will be formed at infinity.

As light rays from infinity or towards infinity seem parallel to the principal axis of the mirror.

Solution

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Solution

Q. A wire is bent in the shape of a right angled triangle and is placed in front of a concave mirror of focal length, f, as shown in the figure. Which of the figures shown in the four options qualitatively represent(s) the shape of the image of the bent wire (These figures are not to scale.) [2018]

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Ans. (4) Distance of point A from the mirror is f2. From mirror formula, 1v+1f/2=1-f⇒1v=2f-1f=1f ∴ v=f Image A'B' of line AB should be I principal axis. Image of F will be formed at infinity. As light rays from infinity or towards infinity seem parallel to the principal axis of the mirror.

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